β-Alanine (or beta-alanine
) is a naturally occurring beta amino acid, which are amino acids in which the amino group is at the β-position from the carboxylate group (i.e., two atoms away, see Figure 1). The IUPAC name for β-alanine would be 3-aminopropionic acid. Unlike its normal counterpart,
α-alanineAlanine is an α-amino acid with the chemical formula CH3CHCOOH. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a nonpolar amino acid...
, β-alanine has no chiral center.
β-Alanine is not used in the
biosynthesisBiosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
of any major
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
s or
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
s.
β-Alanine (or beta-alanine
) is a naturally occurring beta amino acid, which are amino acids in which the amino group is at the β-position from the carboxylate group (i.e., two atoms away, see Figure 1). The IUPAC name for β-alanine would be 3-aminopropionic acid. Unlike its normal counterpart,
α-alanineAlanine is an α-amino acid with the chemical formula CH3CHCOOH. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a nonpolar amino acid...
, β-alanine has no chiral center.
β-Alanine is not used in the
biosynthesisBiosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
of any major
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
s or
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
s. It is formed
in vivoIn vivo refers to experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
by the degradation of
dihydrouracilDihydrouracil is an intermediate in the catabolism of uracil.-See also:* Dihydrouracil dehydrogenase * Dihydrouracil oxidase* Dihydropyrimidinase...
and
carnosineCarnosine is a dipeptide of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues....
. It is a component of the naturally occurring peptides carnosine and
anserineAnserine is a dipeptide found in the skeletal muscle and brain of mammals. It is an antioxidant and helps reduce fatigue. The pKa of the imidazole ring of histidine, when contained in anserine, is 7.04, making it an effective buffer at physiologic pH....
and also of
pantothenic acidPantothenic acid, also called vitamin B
5 , is a water-soluble vitamin required to sustain life . Pantothenic acid is needed to form coenzyme-A , and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats. In chemical structure, it is the amide between...
(vitamin B
5) which itself is a component of
coenzyme ACoenzyme A is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle...
. Under normal conditions, β-alanine is
metabolizedMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
into
acetic acidAcetic acid, CH
3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. It is a weak acid, in that it is only partially dissociated acid in aqueous solution...
.
β-Alanine is the rate-limiting precursor of
carnosineCarnosine is a dipeptide of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues....
, which is to say carnosine levels are limited by the amount of available β-alanine. Supplementation with β-alanine has been shown to increase the concentration of carnosine in muscles, decrease fatigue in athletes and increase total muscular work done.
Typically studies have used supplementing strategies of multiple doses of 400 mg or 800 mg, administered at regular intervals for up to eight hours, over periods ranging from 4 to 10 weeks. After a 10 week supplementing strategy, the reported increase in intramuscular carnosine content was an average of 80.1% (range 18 to 205%).
L-
HistidineHistidine is one of the 20 standard amino acids present in proteins. Nutritionally, histidine is considered an essential amino acid in human infants. After reaching several years of age, humans begin to synthesize it and it thus becomes a non-essential amino acid...
, with a pKa of 6.1 is a relatively weak buffer over the physiological intramuscular pH range. However, when bound to other amino acids this increases nearer to 6.8-7.0. In particular, when bound to β-alanine the pKa value is 6.83, making this a very efficient intramuscular buffer. Furthermore, because of the position of the beta amino group, β-alanine dipeptides are not incorporated proteins and thus can be stored at relatively high concentrations (millimolar). Occurring at 17-25 mmol/kg (dry muscle), carnosine (β-alanyl-
L-histidine) is an important intramuscular buffer, constituting 10-20% of the total buffering capacity in type I and II muscle fibres.
β-Alanine, provided in solution or as powder in gelatine capsules, however, causes paraesthesia when ingested in amounts above 10 mg per kg body weight (bwt). This is variable between individuals. Symptoms may be experienced by some individuals as mild even at 10 mg per kg bwt, in a majority as significant at 20 mg per kg bwt, and severe at 40 mg per kg bwt. However, an equivalent amount (equimolar) to 40 mg per kg bwt, ingested in the form of histidine containing dipeptides in chicken broth extract, did not cause paraesthesia.
It is probable that the paraesthesia, a form of neuropathic pain, results from high peak blood-plasma concentrations of β-alanine since greater quantities, ingested in the form of the β-alanine / histidine (or methylhistidine) containing dipeptides (i.e. carnosine and anserine) in meat, do not cause the same symptoms. In this case the β-alanine absorption profile is flattened but sustained for a longer period of time, whereas, the β-alanine samples in the studies were administered as gelatine capsules containing powder. This resulted in plasma concentrations rising rapidly, peaking within 30 to 45 minutes, and being eliminated after 90 to 120 minutes. The paraesthesia caused is no indication of efficacy since the published studies undertaken so far have utilised doses of 400 mg or 800 mg at a time to avoid the paraesthesia. Furthermore, excretion of β-alanine in urine accounted for 0.60%(+/-0.09), 1.50%(+/-0.40) and 3.64%(+/-0.47) of the administered doses of 10, 20, or 40 mg per kg body weight, indicating greater losses occurring with increasing dosage.
Even though much weaker than
glycineGlycine is an organic compound with the formula NH2CH2COOH. With only a hydrogen atom as its side chain, glycine is the smallest of the 20 amino acids commonly found in proteins....
(and thus with a debated role as a physiological transmitter), β-alanine is an agonist next in activity to the cognate ligant glycine itself, for
strychnineStrychnine is a very toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion. The most common source is from the seeds of the...
-sensitive inhibitory
glycine receptorThe glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine. It is one of the most widely distributed inhibitory receptors in the central nervous system and has important roles in a variety of physiological processes, especially in mediating inhibitory...
s (GlyRs) (the agonist order: glycine >> β-alanine > taurine >> alanine,
L-serine > proline).
A high potency artificial sweetener, called
suosanSuosan is calorie-free artificial sweetener derived from beta-Alanine.Suosan is a sodium salt of beta-4-nitroanilide aspartic acid and is 700 times sweeter than sucrose with a bitter aftertaste....
, is derived from beta-alanine.
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